ae2d916985
As discussed in https://github.com/JuliaLang/julia/pull/43786, openlibm's sqrt function is incorrectly rounded for i387. IEEE requires correct rounding for these functions and LLVM relies on it. Fix that by setting the precision in the FPU control word (see e.g. e_ceil.S for similar FPU modifications).
38 lines
838 B
ArmAsm
38 lines
838 B
ArmAsm
/*
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* Written by:
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* J.T. Conklin (jtc@netbsd.org)
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* Public domain.
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*/
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#include <i387/bsd_asm.h>
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//__FBSDID("$FreeBSD: src/lib/msun/i387/e_sqrt.S,v 1.10 2011/01/07 16:13:12 kib Exp $")
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ENTRY(sqrt)
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pushl %ebp
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movl %esp,%ebp
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subl $8,%esp
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fstcw -4(%ebp) /* store fpu control word */
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movw -4(%ebp),%dx
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andw $0xfeff,%dx /* Set precision field to 64 bits (53 bit mantissa).
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We assume it's set to 0b11 (extended precision),
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so zeroing out the low bit of the precision field,
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will correctly set the precision */
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movw %dx,-8(%ebp)
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fldcw -8(%ebp) /* load modfied control word */
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fldl 8(%ebp)
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fsqrt
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fldcw -4(%ebp) /* restore original control word */
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leave
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ret
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END(sqrt)
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/* Enable stack protection */
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#if defined(__ELF__)
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.section .note.GNU-stack,"",%progbits
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#endif
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